Nature of eclipsing pulsars

We present a model for pulsar radio eclipses in some binary systems, and test this model for PSRs B1957+20 and J2051-0827. We suggest that in these binaries the companion stars are degenerate dwarfs with strong surface magnetic fields. The magnetospheres of these stars are permanently infused by the relativistic particles of the pulsar wind. We argue that the radio waves emitted by the pulsar split into the eigenmodes of the electron-positron plasma as they enter the companion's magnetosphere and are then strongly damped due to cyclotron resonance with the ambient plasma particles. Our model explains in a natural way the anomalous duration and behavior of radio eclipses observed in such systems. In particular, it provides stable, continuous, and frequency-dependent eclipses, in agreement with the observations. We predict a significant variation of linear polarization both at eclipse ingress and egress. In this paper we also suggest several possible mechanisms of generation of the optical and $X$-ray emission observed from these binary systems.Comment: 12 pages, 5 figures, submitted to Ap

Radio pulsar drifting sub-pulses and diocotron instability

Contains fulltext : 35501.pdf (publisher's version ) (Open Access)The potential role of a diocotron instability in causing drifting sub-pulses in radio pulsar emission is investigated for aligned magnetic rotators. It is assumed that the out-flowing plasma above a pulsar polar cap consists of an initially axially symmetric, hollow beam of relativistic electron positron pair plasma which carries an electric charge as well as a current. The occurrence of instability depends on shear in the angular velocity distribution of the beam as a function of axial distance. Instability occurs under typical pulsar conditions at mode numbers ≤ 40. It destroys the symmetry of the equilibrium configuration and leads to a carousel of density columns which rotates at fixed angular pattern speed. The process is applied to two pulsars with observed carousels of drifting sub-pulses, and the diocotron instability at corresponding mode number and axial distance is used as a diagnostic for the charge and current density of the polar flow